As is well known, most crustaceans are carniverous from the larval stage until full maturity and in general, must be separated during growth. In the past, separation has been accomplished by placing one animal per petri dish or by keeping the animals in a constant turbulent water flow. It will be appreciated that the density achievable through the utilization of petri dishes or other types of small containers is exceedingly low, and the maintenance of proper water quality is exceedingly difficult, making this system uneconomical. With respect to the turbulation method of separation of the animals, animals are damaged, do not feed well, and consequently, either do not grow rapidly enough or die due to trauma induced by the constant agitation or turbulation.
The problem of raising crustaceans and more particularly, post larval lobsters from birth through the early months is solved in the subject invention by providing a rectangular honeycomb type core habitat or domicile in which the honeycomb or core cavities provide compartments for the animals. In a preferred embodiment, the honeycomb core is composed of opposed cones facing outwardly such that the open end of the cone is adjacent a face of the rectangular core material.
Animals are inserted one per conical compartment formed by the core structure and a screen or mesh is then placed over each of the two opposing faces of the core to maintain the animals within each of the conical compartments. The core and screen combination is then removeably mounted above a false bottom within a tank of water. In one embodiment habitats made in this manner are oriented on end in rows, with space left between the habitats. This provides that the open ends of the compartments lie in vertical planes.
Immediately beneath the habitats formed in this fashion are provided delivery tubes through which food may be injected immediately beneath the habitats. Alternatively, doped food rods may be used. This food is carried upward by air lift circulation provided by aerator tubes, such that as the air bubbles rise, the food, normally live artemia or brine shrimp, is carried upwardly past the habitats, where they either swim through the mesh or are captured by the animals which reach through the mesh. This latter method of feeding is an unexpected finding, in that it was discovered that even the smallest larval lobsters will reach through the mesh to obtain food.
A trap in the form of a screen is provided at the top of the tank to maintain the live food or brine shrimp within the portion of the tank occupied by the habitats, whereas overflow water is filtered and reintroduced to the air lift circulation region so as to provide circulating high quality water and fresh food in the vicinity of the habitats.
By holding animals in the aforementioned double sided cellular core, the density of animals that can be raised successfully increased from 8.5 animals per cubic foot to a density of more than 600 animals per cubic foot.
It was originally thought that a configuration of this type might be unacceptable because it was questionable whether a mesh size could be chosen which would allow the artemia to swim in but restrain the post larval crustacia. It was found that an appropriate mesh could be selected and that food will penetrate the mesh and, more importantly, that after a few days, even the smallest of the animals will learn to pluck the food from the water adjacent the screen by reaching through the screen. Thus, it is an unexpected result that food can successfully be transferred into a semi-closed habitat without the necessity of providing food directly into the habitat itself.
Another unexpected result when utilizing the type of habitats described, is the fact that the animals clean the habitat by pushing unwanted debris out through the screen. One plausible explanation for the self-cleaning aspect of the subject habitat is the slanting of the floor portion downwardly along with the animals' natural desire for a clean habitat. Thus, sediment and other materials which would be deleterious to the animals' health, are removed from the habitat by the animal itself and this phenomenon, although completely unexpected, results in a much higher yield. Another aid to cleaning is that turbulent water within the compartment provides cleaning action. As will be appreciated, gaffkemia and other diseases are common and in general, are in part aggravated by the contamination of the habitat. However, with the slanted floor provided by the conical habitat, cleaning occurs either through action by the animals or by the slight turbulence produced by the air bubbling in which the sediment gradually works its way towards the base of the cone and out through the screen.
Prior to testing, there was also some uncertainty as to the ability of the animals to survive in a compartment in which the floor was permanently slanted, that is to say, not level. After extensive testing, it is a finding of this invention that these animals can, in fact, survive and thrive with the configuration shown and that the non-level floor appears not to be a negative factor in animal health. While the subject invention has been described in terms of a conical cored honeycomb, this invention is not limited to the particular honeycomb structure.
By the utilization of sealing face plates of glass, plastic, etc., it is possible to retain the animals in the water bath at all times during handling operations. It will be appreciated that each screen can be provided with a removeable cover plate which may be slid over the screen to maintain the animals in a water bath prior to removal of the habitat from the tank. The habitat can then be laid on one side, and the uppermost cover plate can be removed to permit access to all the animals in compartments facing upwards. The core can then be reversed for access to animals on the opposite side.
It will thus be appreciated that with the subject system for relatively delicate small animals, the number of handling operations is minimized.
In summary, the subject habitats provide early separation of the animals, live feedings through a selective screen, and high density of 288 animals per square foot of cellular core material, permitting a density in excess of 600 animals per cubic foot during the first few months of life. Moreover, water quality in each cell is maintained by turbulent mixing of water generated by the air flow and there is ready access to any core segment in the array without operational interference to other sections of the domicile. Thus, there is complete random access to any animal without disturbance to others.
It is therefore an object of this invention to provide a cellular domicile for the high density raising of aquatic animals;
It is another object of this invention to provide a habitat and feeding system in which freshly filtered and aerated water containing live food is made to flow by the face of habitats which are sealed by a selective screen;
It is a still further object of this invention to provide an air lift circulation feeding system for habitats;
It is a still further object of this invention to provide a method for increasing the density of animals and the rearing of animals from birth to a predetermined age;
It is another object of this invention to provide a habitat for the rearing of small animals in which apparatus for introducing food directly into the individual habitats is not needed;
It is another object of this invention to provide a cellular habitat in which the floor portions thereof need not be maintained in a horizontal plane; and
It is a still further object of this invention to provide a habitat comprising a core of cellular material with screens on opposing faces and having an opposing cone structure so as to increase the capacity of the area allocated for raising animals.
These and other objects of the invention will be more fully appreciated in view of the following specification taken in conjunction with the appended drawings.